Composite chelating compositions

ABSTRACT

CHELATING COMPOSITIONS OF ENHANCED STABILITY IN USE, NAMELY, ENHANCED CAPACITY AND ABILITY TO HOLD A HEAVY METAL IN CHELATED FORM IN SOLUTION AT HIGH PH ARE FORMED BY USING IN COMBINATION PAIRS OF LIGAND SOURCES OF LIGAND TYPES, SPECIFICALLY, HYDRAZINE REACTION PRODUCTS OF SYNTHETIC POLYAMINO POLYCARBOXYLIC ACIDS TOGETHER WITH THE SYNTHETIC POLYAMINO POLYCARBOXYLIC ACIDS AND ACID SALTS IN A WIDE RANGE OF PROPORTIONS.

Feb. 23, 1971 F. c. BERSWORTH comrosni: CHELATING COMPOSITIONS Filed001.. a. 1967- I A= STANDARD SOLUTION B= 2% EDTA-TETRAHYDRAZIDE I C= 2%EDTA-- TETRAHYDRAZIDE f ARROW mmcgTes pnzcupmnou 4o e0 8O VOLUME BASEINVENTOR.

. FREDERICK C. BERSWORTH ATTORNEY United States Patent Oflice 3,565,813COMPOSITE CHELATING COMPOSITIONS Frederick C. Bersworth, 120 WashingtonSt., East Orange, NJ. 07017 Filed Oct. 2, 1967, Ser. No. 672,059 Int.Cl. C07c 101/24; C09k 3/00 US. Cl. 252-182 7 Claims ABSTRACT OF THEDISCLOSURE DETAILED DESCRIPTION OF THE INVENTION I have discovered thatchelating compositions consisting essentially of a pair of components 1)a hydrazine reaction product of a polyamino polycarboxylic acidcompositions having a formula answering to the following:

CHzGOM lHzCOM wherein R is selected from the group consisting of H andCOM m COM and COM is independently selected from the group consisting ofCOOH, COONa, -COOK, COONH and COOAlkyl, not more than two COMs being CHOH, with a compound selected from the group consisting of hydrazine,alkyl substituted hydrazines having 1-8 carbon atoms, guanidine,biguanidine, and urea, wherein at least one of said COMs in acid form isreacted.

This amide reaction product of hydrazine and the polycarboxylic acid, incombination with a polyamino polycarboxylic acid chelating agent whichis the acid or salt formed of the material reacted with the hydrazine inthe first instance. The polyamino polycarboxylic acid compounds answerto the following formula:

CHzCOM N-R (IJH2COM wherein R is selected from the group consisting of Hand CHzC OM Patented Feb. 23, 1971 and C-OOAlkyl, not more than two COMsbeing -CH OH.

Generally, in making the compositions according to this invention mostfavorable results are obtained by combining in the composition thepolyamino polycarboxylic acid which is used in the condensation productwith the hydrazine and the polyamino polycarboxylic acid in about a 1:1molar ratio, though broadly the range may be from 5%, by weight ofeither one with by weight of the other. This appears to be a function ofproviding a large number of similar ligands of similar reactability sothat the chelating function performed by one of the molecules isenhanced by the related chelating mechanism of the other.

In more quantitative terms, in investigating these compositions, thestability of these solutions was referred to measurements of thestability of the ion Fe(III)-EDTA and Fe(III) NTA solutions containingvarying amounts of the hydrazides. To perform the measurements it wasnecessary to use a standard solution of the Fe(III)- ligand where theligand is ethylene diamine tetraacetic acid, or nitrilotriacetic acid,so that controlled amounts of ligand this would be a particularhydrazide, could be added which would allow comparisons of solutionswith differing ligand or of varying proportions of the ligand In theexperimental work reported in the following examples the standardsolutions contained five grams of ligand and a stoichiometric amount offerric nitrate. The solution thus was a 1:1 ratio of iron (Fe(III)) tothe ligands. The solution was made in 50 milliliters of water.

On this basis the standard solution of the weight to weight ratio ofligand to ligand is the method by which the concentration of ligand insolution is identified. For example, if 0.01 gram of EDTA-tetrahydrazidewas added to the standard solution we would have 0.01 gram ligand;

or 2% EDTA-tetrahydrazide per total ligand in solution. (Strictlyspeaking the percentage is slightly less than 2 because the weight oftotal ligand in solution is 0.510 gram and not 0.500 gram, but thissmall deviation is neglected here.)

A better understanding of details of the composition will be obtained byreference to the drawing wherein the graphical representation oftitration of standard solution with sodium hydroxide is represented asCurve A; Curve B is that obtained when 2% by weight of EDTA-tetrahydrazide is added to the standard solution titrated with the samestandard base; C shows the shift in the second inflection of thetitration curve when EDTA-tetrahydrazide concentration is againincreased.

CURVE A (EXAMPLE I) A standard solution of ligand and ligand alonetitrated with 0.1123 molar sodium hydroxide.

CURVE B (EXAMPLE II) A 2% by weight, 0.01 gram of ethylenediaminetetraaceticacidhydrazide was added to the standard solution andtitrated with the same standard base.

CURVE C (EXAMPLE III) The standard solution was titrated when theethylene diamine tetraacetic acid tetrahydrazide condensation wasincreased to approximately 10 percent.

The experimental data involving the titration curve developed inExamples I, II and III are plotted herewith and in the drawingconstitute the curves and are labeled Curves A, B and C.

The reactions induced involve mixed ligand complexes of- Fe(III) usinghydrazides and the chelating acids. The following theory outlines amechanism for the phe- Schwarzenbach and Heller (Helv. Chim. Acta, 34,

4 Note that an Fe(III)-EDTA (1:1) solution can be stabilized to boilingat a rather high pH simply by addition of 7 to weight percent ofdisodium EDTA dihydrazide.

Continuing with investigations in the Fe(III)-EDTA- ligand systems thenext substituent studied was the 576 (1951)) studied the interaction ofOH- on totally 5 CaEDTA dihydrazide (pilot plant quality). As little ascoordinated Fe(III)-EDTA: 2% of the CaEDTA dihydrazide will preventprecipitate ai 0 O- Apparently addition of the EDTA-tetrahydrazideinhibits from forming in an Fe(III)-EDTA solution at pH 11. the secondreaction above, most likely through coordina- Higher percentages arerequired to stabilize such a solution of the hydrazide group. tion toboiling but this material seems adequate for lend- Curve D in FIG. 1 issimply for reference, it reping stability to Fe(III)-EDTA systems.resents the titration of 0.50 g. of EDTA-tetrahydrazide If 10% sodiumphosphate (monobasic) is added to a and 0.581 g. of Fe(NO -9H O with0.1123 M NaOH solution containing Fe(III)-EDTA in a 1:1 mole and (a 1:1mole ratio of the tetrahydrazide to 'Fe(III) The 2% CaEDTA dihydrazide,the solution can be boiled at EDTA-tetrahydrazide was used for this partof the study pH 10 Without precipitate formation and at pH 11 thebecause it is of higher purit than the dihydrazides. The solutionbecomes only slightly cloudy with boiling.

n y 1 e v n I a n behavior of the EDTA-Fe(lll) system with varying per-Investigations were carried out in F6(IlI)-IllIIllOl1 centages of thetetrahydrazide at high pH values is preaceticacid (NTA) systems, theresults were not as good sented in the following table. 37 as with theFe(III)-EDT A systems, but the solutions can TABLE I be stabilized ifthe percentages of the hydrazides added are increased. With 30% ofCaEDTA dihydrazide 20 ll tliil y draada pH 11 pH NaH Po, added to thestandard NTA-Fe(III) solution 0 O4 1 t R t d I um 0.5 gram NTA, 1.057gram Fe(NO -9H O) the solu- 6::::::::::::::::::::::: aldifiiiaiLiiiii a?40 can be bwught to PH 11 with immediate 10 Dark red s0luti0n.... Darkred soluti n. cipitate formation, but upon standing the solution turnsPpt. only upon addition of alarge amount of base. cloudyg Original NTAnf ratio must I s greater t an 1:1 to a ow sta iization o the solution y:3 8 6 g gigz gf fgs gggg g gygg tfii addition of a small percentage ofhydrazide. be boiled at pH 11 without appreciable decomposition. It W111be apparent from these (.lata that the addmon This behavior is notexhibited in a simple Fe(III)-EDTA of snjlan amounts of EDTA hydrazldesto F6 (HD'IEDTA System even if the EDTA is in great excess solutionsstabilizes these solutions to high hydroxide ion trations as well as toheating at high pH. The pro- When Fe(III)-EDTA solutions are treatedwith diconcen a sodium EDTA dihydrazide the results obtained are quitezgi f i ga 222 3 i 1 3 5 i gi similar to those obtained with thetetrahydrazide. The sgcond enterin 6 wilich i s fr 1 l e titrationcurves are more difiicult to interpret because the inner cooifination Sg F (fin f we are now adding a salt of EDTA to the solution which thatonce two 5 6 ar che'd t 2 can vastly change the early region of thetitration curve elation O1 mer formg gg 3 e as the percentage of thedihydrazide is increased. How- P y S 1 I g Sequen preclpl' ever, theassumption that the second hydroxy group is gfi be a arent from theuanft It being inhibited from being attached directly to the q 1 a l e SR Fe(III) ion can still be made due to the similarity of m 9 Filth f:. gDdthat i the complexing agent. Table II was compiled from data 9 u m 0 ae 9 0 6 .amen a Obt d b v r th e centa of di odium EDT A ligand namely acompound like ethylenediaminetetra- 2: g 1 acetic acid or thepolycarboxylic polyamino acetic acid 1 y razl e m 6 Stan at e( so ucompound together with a hydrazine reaction product of TABLE II acompound of the family of chelating acids gives an en- Pement hancementof the heavy metal chelating ability of the comdihydrazide P P position,which, if it is explainable at all, is on the basis 2 oranggmd {mamaprecipmm of a mechanism involving the plurality of ligand moietiesBlmgi-redsolution 33 3 (1 01mm in the solution with the surplusavailable to bind tightly S with whatever metal is to be chelated. Whileideally I HEAT STABILITYI Percent dihydrazide pH 9 pH 10 pH 11 2Orange-red solution Yellow solution-.. Radish ppt. 6.-. o d0 Turbidity.10 Red-orange solution Orange solution... Orange solution.

1 Efiect of boiling the solution at the given pH value. 2 At slightlyhigher pH this solution may ppt. on standing.

Ligand; Ligandz (1) nitrilotriacetic acid (1) mono-di and tri hydrazinesof nitrilotriacetio acid.

(2) ethylene diamine tetraacctic (2) mono, di, tri and tetraacid.hydrazin s of ethylene diamine tetraacetic acid. (3) hydroxyethylethylene diamine (3) mono, di, tri and tetra hytriacetie acid. drazinesor hydroxyethyl ethylene diamine triacetic ac (4) di-ethylene tri-aminepent- (4) mono, di, tri, tetra and penta acetic acid. hydrazine reactionproducts of diethylene triamine pentacetic acid.

In general, for the preparation of these compositions it is perhaps mostdesirable to use the preformed hydrazide prepared in accordance with theprocedure described in my United States patent application Ser. No.580,829, filed Sept. 20, 1966, which issued on Nov. 7, 1967 as UnitedStates Pat. No. 3,351,658. Generally, the precaution to be observed inthe preparation of the hydrazides is to induce a reaction whichseparates Water of reaction between hydrazine and the acid form so as todevelop a CONHNH grouping in the composite molecule. In converting apolyamino polycarboxylic acid compound to this form it is generallysimplest to work from an acid form, of the compound specifically a mono,di, tri or tetra acid form of the ethylene diamine tetraacetic acidcompound. The presence of a neutralized group, or two, or three, in themolecule does no harm, but it does not lead to the formation of theamide group which is sought. In admixture then with the unmodifiedpolyamino polycarboxylic acid the compounds place in the solution alarge number of ligands which are reactive and reactable to combine withions such as those of iron which require a large number of ligands tohold them chelated and, particularly, to hold them chelated at highalkaline pH values.

Hence the preparation of composition involves merely mixing a certainmolar proportion of the hydrazide with a molar proportion of theethylene diamine tetraacetic acid. Generally, it will be simplest tohave then on a 1:1 molar ratio although it is perfectly reasonable tohave a small but effective amount of the free chelating acid, as low asfive percent of the weight of the hydrazide composition, to a range atthe opposite extreme wherein the chelating composition will be largelythe free ethylene diamine tetraacetic acid with as little as fivepercent by weight of the hydrazide. The preferred range of compositionin the spectrum possible is in the range where there are approximately1:1 molar ratios of the two compounds present and preferably it is asoluble acid form of the amino polycarboxylic acid mixed on a 1:1 molarratio with the fully reacted hydrazide form thereof. I say a solubleacid form because at very low pH EDTA is not water solutble and itsneutralization to Na or Na form is needed for solubilizing.

It will be apparent from an inspection of the formulas that where eachof the acids can have a plurality of hydrazide and salt forms and eachof the acids can also have a variety of salt forms that the mixtures ofthe hydrazides with the acids and the acid salt forms produces anextraordinarily large number of combinations. This however is reducibleto the relatively simplified formula for the preparation of thesesynergistic compositions, which involves merely the 1 for 1 molarmixture of the two.

In the preparation, the physical mixing of the two com- 6 positionsthrough careful blending and use thereafter is perfectly adequate.

The preferred acids to use, or any acid salt thereof, for the formationof the hydrazine :reaction products to be mixed with the acids or acidsalts are the following: iminodiacetic acid; hydroxyethylnitrilodiaceticacid; nitri1o triacetic acid; dihydroxyethylnitrilomonoacetic acid;ethylenediaminetetraacetic acid, diethyltriaminepentaacetic acid,triethylenetetraamine hexaacetic acid and, monoand dihydroxyethylvariants thereof.

I claim:

1. A composition of a pair of components consisting essentially of afirst component selected from a group of compounds consisting of thereaction product of a compound having a formula given by:

and --COM is independently selected from the group consisting of COOH,COONa, COOK, COONH and C-OO-Alkyl, not more than two COMs being CH OH,with a compound selected from the group consisting of hydrazine, alkylsubstituted hydrazines having 1-8 carbon atoms, guanidine, biguanidine,and urea, wherein at least one of said --COMs is reacted, said reactionbeing conducted under conditions wherein the reactants are freed ofwater, the conditions being such that water is liberated in thereaction, the reaction being conducted at a temperature sufficient toeliminate water of reaction with acid forms, and alcohol of reactionwith ester forms, and a second component selected from a group ofcompounds consisting of and COM is independently selected from the groupconsisting of COOH, COONa, COOK, COONH said first component beingpresent in the range of 5 percent to percent by weight, and the secondcomponent being present in the range of 95 percent to 5 percent, byweight.

2. A composition in accordance with claim 1 consisting essentially of(1) the amide product of reaction of one mole of ethylene diamine tetraacetic acid and two moles of hydrazine, and (2) ethylene diaminetetraacetic acid.

3. A composition in accordance with claim 1 consisting essentially of(l) the amide product of reaction of one mole of hydroxy ethyl ethylenediamine triacetic acid and one mole of hydrazine, and (2) hydroxyethyl-ethylene-diamine triacetic acid.

4. A composition in accordance with claim 1 consisting essentially of(1) the amide product of reaction of one mole of hydroxy ethyl ethylenediamine triacetic acid and two moles of hydrazine, and (2) hydroxy ethylethylene diamine triacetic acid.

5. A composition in accordance with claim 1 consisting essentially of(1) the mono amide of hydrazine and ethylene diamine tetraacetic acid,and (2) ethylene diamine tetraacetic acid.

6. A composition in accordance with claim 1 consisting essentially of(1) the tri amide of hydrazine and ethylene diamine tetraacetic acid,and (2) ethylene diamine tetraacetic acid.

7. A composition in accordance with claim 1 consisting essentially of(1) the tetra amide of hydrazine and emylene diamine tetraacetic acid,and (2) ethylene diamine tetraacetic acid.

References Cited UNITED STATES PATENTS RICHARD D. LOVERING, PrimaryExaminer I. GLUCK, Assistant Examiner U.S. Cl. X.R.

